The field of the present invention is control mechanisms for poppet valves as may be employed in internal combustion engines.
Internal combustion engines have been developed for vehicles and other uses where the engine is expected to run at a wide range of engine speeds. Among other difficulties created by the demand for a wide range of operating speeds is the need for the valve actuating mechanisms to accommodate inertial forces varying with engine speed. Of particular difficulty are the valve closing springs. Spring forces remain constant regardless of the engine speed.
Because of the inability to vary the valve spring force with variations in the inertial load, design choices have been required which require compromise between high speed valve performance and more efficient, less expensive designs. If the valve control mechanism is designed for high speed performance, stronger and harder materials are needed to overcome the stronger valve spring. The increased forces and frictional forces of such a design require more power from the engine thereby reducing its efficiency. By designing the valve mechanism to operate efficiently at lower speeds, higher rpm's may damage the mechanism not designed for such operation and the valves may experience float or rebound. Hence, design compromises have been required to accommodate the foregoing problems without the ability to vary spring forces with engine speed.